Microelectromechanical systems (MEMS) include micromechanical elements, actuators, and electronics. Micromechanical elements may be created using deposition, etching, and/or other micromachining processes that etch away parts of substrates and/or deposited material layers or that add layers to form electrical and electromechanical devices. One type of MEMS device is called an interferometric modulator. As used herein, the term interferometric modulator or interferometric light modulator refers to a device that selectively absorbs and/or reflects light using the principles of optical interference. In certain embodiments, an interferometric modulator may comprise a pair of conductive plates, one or both of which may be transparent and/or reflective in whole or part and capable of relative motion upon application of an appropriate electrical signal. In a particular embodiment, one plate may comprise a stationary layer deposited on a substrate and the other plate may comprise a metallic membrane separated from the stationary layer by a transparent medium (e.g., an air gap). As described herein in more detail, the position of one plate in relation to the other plate can change the optical interference of light incident on the interferometric modulator. Such devices have a wide range of applications, and it would be beneficial in the art to utilize and/or modify the characteristics of these types of devices so that their features can be exploited in improving existing products and creating new products that have not yet been developed.
An interferometric modulator display device generally comprises multiple pixels, in which each pixel is operable to provide a range of visual colors, for example, by changing the position of a corresponding plate (e.g., the metallic membrane) in relation to another plate (e.g., the stationary layer) to shift a color perceived by a user. Conventional interferometric modulator display devices, however, typically do not have a brightness control (for each pixel) that is independent of pixel color—i.e., in conventional interferometric modulator display devices the brightness of a pixel is usually controlled by shifting a color of the pixel to an unperceivable color. Consequently, brightness control in conventional interferometric modulator displays is generally limited.
Accordingly, what is needed is an improved technique for providing brightness control in an interferometric modulator display. The present invention addresses such a need.